The field of the present invention is methods for the delivery or placement of therapeutic or diagnostic agents into a living body.
Some medical procedures employ the infusion of therapeutic agents into living bodies over periods of time, making a syringe inconvenient and/or inappropriate. Such procedures have been used for the infusion of insulin, for example. In other cases, monitoring of internal body conditions with small sensors or other devices also makes syringes and like devices inappropriate for continuing access to subcutaneous tissue. To provide access in either circumstance, ports have been devised which provide support for a flexible cannula implanted in the body. Ports typically provide a housing which has a mounting side that is held by tape, dressings or direct adhesive against the body. A flexible cannula extends from the housing into the body.
Ports used for infusion may be employed in combination with a delivery tube extending to the housing of the port and in communication with the cannula as a complete infusion set. The delivery tube of such an infusion set is in communication with the flexible cannula through an infusion fluid chamber in the port to deliver therapeutic agents. Diagnostic agents such as biosensors may be delivered in like manner.
To place such ports or infusion sets including such ports, insertion sets have been used. An insertion set typically includes the port and necessarily includes a rigid sharp such as a needle which is placed through the flexible cannula for insertion into the body. The needle typically extends through a resilient barrier such as a resealable resilient mass, through a chamber and then axially through the cannula. Once the cannula has been positioned in the body, the port is positioned and the needle can be withdrawn. The resealing of the mass as the needle is withdrawn prevents fluid from leaking from the port while remaining in position at the site. Once the port has been placed with the flexible cannula extending into the body, the agent or agents can be delivered.
A first type of insertion set includes an infusion set having the port and a delivery tube in communication with the cannula. The insertion set needle accesses the housing through a different path than the delivery tube. The seal is typically bypassed by the delivery tube in this instance. Alternatively, the insertion set is used with a port rather than a complete infusion set. The delivery tube is placed after insertion of the port to complete an infusion set. The same path is used for the insertion needle as part of the insertion set as is used for communicating the tube of the infusion set with the cannula. In this latter case, the delivery tube is associated with a hub which includes a member able to pierce a resealable resilient mass for communication between the delivery tube and the cannula once the insertion set has been disassembled through retraction of the needle.
Mechanisms referred to as inserters have been devised to rapidly insert the needle and cannula into the body at the site. For the infusion of insulin in particular, diabetics self medicate. Consequently, they, a family member or other care provider places the port for infusion. This can be emotionally and physically difficult when repeated infusions are required over long periods of time. Inserters alleviate this burden somewhat by making the placement of the needle automatic and quick. Further, pressure by the inserter about the targeted site reduces the sensation of pain.
Inserters typically include a housing with a driver slidable in the housing. The driver includes a socket to receive the insertion set. A spring is operatively placed between the housing and the driver to advance rapidly an insertion set positioned in the socket. A latch then controls the advancement of the driver. One complete system including an infusion port, an insertion set having the infusion port and an insertion needle, and an inserter is illustrated in U.S. Pat. No. 6,293,925.